The invention relates to copy quality and, more particularly, to eliminating deletions and residual fuser oil contamination from xerographic prints.
In using reproduction machines, there are various types of system shut downs, cycle downs, or malfunctions that can occur in a variety of operating modes. Operator involvement in returning the machine to a print quality status can often be extensive particularly in machines with various accessories such as sorters, collators, finishers and document handlers. The problem of maintaining the integrity of the run in process, and minimizing down time and operator involvement can be significant.
In particular, defects in output copies may be caused by machine activity. For example, defects on copy sheets, typically deletions, may be found on prints or copies made on sheets that have been pre-fed in the paper trays and have remained in that position long enough to have acquired a curl. Also, when the system has remained idle for some length of time, the first prints or copies out, whether or not the sheet s have been pre-fed, may exhibit contamination by excess fuser lubricant that has accumulated in the fuser mechanism (on the fuser roll). The amount of elapsed time required for these effects to develop varies and is dependent upon several factors. Those factors may include environmental conditions, materials used, and type of system.
One or both of these effects may or not be a problem for the customer. Both conditions could occur during standby or power down. The amount of time may vary from as little as 30 minutes to 4 hours. Sensitivity by the customer to these effects may vary upon the criticality of the print or copy jobs. For example, accounting or internal administrative sheets of low importance may be the first sheets through the system in specific job sets. Another factor affecting sensitivity may be the use of special stock in one or more trays which must be fed in specific sequence and the invocation of the feature may cause disruption to the copy process. Such disruption may occur with multipart forms, such as carbonless, certificates, etc., or numbered stock, such as checks, stock certificates, etc., or any other stock that must be fed in sequence from one or more trays.
Job recovery in a copy sheet jam environment is well known in the prior art and generally requires the removal of documents or copy sheets stopped in several places in the machine. Jam recovery also often requires the reordering of documents as well as the purging of some or all of copies in process in the machine. For example, U.S. Pat. No. 5,142,340, assigned to the same assignee as the present invention, discloses the automatic purge of copy sheets through the fuser after a jam to rid the system of potentially contaminating materials.
Various other techniques of jam clearance exist in the prior art. For example, U.S. Pat. No. 4,627,711 to Schron, assigned to Xerox Corporation, discloses a control system for controlling the shutdown of a paper path system in a copy machine when a paper handling fault occurs. Upon detecting a malfunction or jam, the control system evaluates the status of all sheets in a sheet handling system and makes determinations whether to hold sheets from entering into a boundary between two zones or to drive a sheet at a boundary into a next zone.
U.S. Pat. No. 4,786,041 to Acquaviva et al., assigned to Xerox Corporation, discloses a document handler jam clearance and job recovery system. Upon the occurrence of a paper jam, the system determines whether a document has jammed in a first, second or third document path jam zone and automatically provides a preliminary job recovery operation before the document handler is fully stopped. Document feeding zones are independently operated to feed unjammed documents in a third jam zone to a stacking tray or to feed unjammed documents in the third jam zone to a stacking tray or to feed unjammed documents in the first jam zone to a platen, so that documents are directed to be operator removed from only one zone.
U.S. Pat. No. 4,275,879 to Yamashita et al. discloses an apparatus for detecting an abnormal paper feed. Upon detecting the occurrence of an abnormal paper feed, the apparatus sends forth an abnormality signal only after all preceding sheets have been processed and delivered to an output stacker from entering into a boundary between two zones or to drive a sheet at a boundary into a next zone.
One deficiency in these prior art devices is the restriction of the system recovery to fault and jam recovery. Another difficulty in prior art devices is the inability to account for multiple non jam occurrences such as fuser oil contamination and copy sheet curl and to take corrective measures. Another difficulty is the lack of the capability to optionally or selectively monitor various system parameters for purging unwanted copy sheets.
It is an object, therefore, of the present invention to be able to adapt a given machine to a specific operating environment to be able to purge copy sheets from the system unrelated to a copy sheet jam event. Another object of the present invention is to be able to monitor system parameters such as machine down time or copy sheets in pre-feed rolls to purge the system of undesirable copy sheets. Another object of the present invention is provide the option to enable various machine parameters to purge undesirable copy sheets from the system unrelated to a copy sheet jam event. Other advantages of the present invention will become apparent as the following description proceeds, and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.